I have a 20 tall with 1 guppy, 1 molly, 4 guppy fry, 3 ghost shrimp, 1 blue shrimp, 2 glass catfish, and 2 sword tails and a few snails that have been breeding in my tank. My tank was not cycled but i used old water and aqaurium gravel from another tank i still have running. Been up for about 2...